Congrats on your new rifle, they're a lot of fun you'll enjoy it. It's all a standard height, just buy the rear sight you want. Also, that's not just a front sight, it's your gas block. The front sight/gas block is held on with either set screws, clamping screws or it's a press fit, and it may or may not be pinned in place with tapered pins. If it's held on with set screws or clamped on, you can just buy a replacement low profile gas block and swap out the parts. If it's pressed on you will need a gunsmith with a hydraulic press to remove the sight that's on there.